Insert data into an existing row

[charles_i]

How do I write the code to insert data into a specific row which is based on a Session number? I'm trying to do something like this but the WHERE syntax is wrong.

//get $_SESSION['session'] number (which is the ID number )
if (isset($_SESSION["session"])){
$currentSession = $_SESSION['session'];
echo "Session on eval page " . $currentSession . "<br>";
}

//put $_SESSION['session'] number into specified row
$sql = "INSERT INTO congress(session) VALUES('on') WHERE id ($currentSession)";
$session = mysql_query($sql)
or die(mysql_error());

I have started the row on one page with just the ID number - used it as a Session number and left the rest of the row empty. When the form is filled out on the second page I want to fill the empty fields in the row identified by the Session.

Thanks

[barbara1712]

use update query instead of insert

$sql = "update congress set session='on' WHERE id=$currentSession"; 

[Christopher Hill]

You will need to use the UPDATE command, not the INSERT.

mysql_query("UPDATE `congress`
SET `session` = 'on'
WHERE `id` = '" . mysql_real_escape_string($currentSession) . "'
LIMIT 1") or die(mysql_error());